Battery system and method for determining abnormality of battery

ABSTRACT

A battery system, capable of detecting a pore generated in an outer package film in an early stage, includes: a battery including a plurality of laminated cells arranged along a thickness direction and connected in series, and a plate arranged between a pair of the laminated cells; a first voltage sensor configured to measure a first voltage between a terminal of a reference cell belonging to the plurality of laminated cells, and the plate; a second voltage sensor configured to measure a second voltage between a terminal of the reference cell, and among the pair of laminated cells facing the plate, the laminated cell in the reference cell side; and an electronic control unit including a first obtaining unit configured to obtain the first voltage from the first voltage sensor.

CROSS REFERENCE TO RELATED APPLICATIONS

This nonprovisional application claims priority to Japanese PatentApplication No. 2020-024187 filed on Feb. 17, 2020, with the JapanPatent Office, which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present disclosure relates to a battery system and a method fordetermining an abnormality of a battery.

BACKGROUND ART

A laminated cell is a cell in which a power generating element is sealedwith an outer package film, and the use of the outer package filmfacilitates thinning and space saving of a battery. For example,Japanese Patent Application Laid-Open (JP-A) No. 2003-187762 discloses anon-aqueous electrolyte battery in which a battery element including acathode, an anode, and an electrolyte, are stored in a laminated outerpackage, and a moisture absorbing member is arranged distanced from thebattery element. In addition, Japanese Patent Application Laid-Open(JP-A) No. 2003-187762 discloses about reducing permeation of moistureinto the outer package by doubling a moisture absorbing agent arrangedaround a sealing part.

Also, as an abnormality detecting device of secondary battery, a deviceutilizing a voltage value and a current value of the secondary batteryhas been known. For example, International Publication No. WO2019/138286 discloses an abnormality detecting device of secondarybattery including a first detecting measure configured to detect avoltage value of secondary battery which is a first observation value, asecond detecting measure configured to detect a current value ofsecondary battery which is a second observation value, calculation unitconfigured to calculate a presumed voltage value using a regressionmodel, and a determination unit configured to obtain a different betweenthe voltage value of the first observation value and the presumedvoltage value obtained previously, and to determine an abnormality ofthe secondary battery when the value exceeds a specified threshold valuerange.

SUMMARY OF DISCLOSURE Technical Problem

Since an outer package film is thin, for example, a pore may begenerated due to a foreign substance mixed during the production of acell. The present disclosure has been made in view of the abovecircumstances, and a main object thereof is to provide a battery systemcapable of detecting a pore generated in an outer package film in anearly stage.

Solution to Problem

In order to achieve the object, the present disclosure provides abattery system comprising: a battery including a plurality of laminatedcells arranged along a thickness direction and connected in series, anda plate arranged between a pair of the laminated cells; a first voltagesensor configured to measure a first voltage that is a voltage between aterminal of a reference cell belonging to the plurality of laminatedcells, and the plate; a second voltage sensor configured to measure asecond voltage that is a voltage between a terminal of the referencecell and, among the pair of laminated cells facing the plate, thelaminated cell in the reference cell side; and a determination device;and the determination device includes: a first obtaining unit configuredto obtain the first voltage from the first voltage sensor, a secondobtaining unit configured to obtain the second voltage from the secondvoltage sensor, and a first determining unit configured to determine anabnormality based on the first voltage and the second voltage.

According to the present disclosure, the determination device determinesan abnormality based on the first voltage and the second voltage so asto allow a battery system to detect a pore generated in an outer packagefilm in an early stage.

In the disclosure, the battery system may further comprise a thirdvoltage sensor configured to measure a third voltage that is a voltagebetween a terminal of the reference cell and, among the pair oflaminated cells facing the plate, the laminated cell in the oppositeside of the reference cell, and the determination device furtherincludes: a third obtaining unit configured to obtain the third voltagefrom the third voltage sensor, and a second determining unit configuredto determine an abnormality based on the first voltage and the thirdvoltage when the first determining unit determines an abnormality.

The present disclosure also provides a battery system comprising: abattery including a plurality of laminated cells arranged along athickness direction and connected in series, and a plate arrangedbetween a pair of the laminated cells, a first voltage sensor configuredto measure a first voltage that is a voltage between a terminal of areference cell belonging to the plurality of laminated cells, and theplate, a third voltage sensor configured to measure a third voltage thatis a voltage between a terminal of the reference cell and, among thepair of laminated cells facing the plate, the laminated cell in theopposite side of the reference cell, and a determination device; and thedetermination device includes: a first obtaining unit configured toobtain the first voltage from the first voltage sensor, a thirdobtaining unit configured to obtain the third voltage from the thirdvoltage sensor, and a second determining unit configured to determine anabnormality based on the first voltage and the third voltage.

According to the present disclosure, the determination device determinesan abnormality based on the first voltage and the third voltage so as toallow a battery system to detect a pore generated in an outer packagefilm in an early stage.

In the disclosure, the battery may include a plurality of the plate, andthe first voltage sensor may select the plate for measuring the firstvoltage from the plurality of the plate.

The present disclosure also provides a method for determining anabnormality of a battery including a plurality of laminated cellsarranged along a thickness direction and connected in series, and aplate arranged between a pair of the laminated cells, the methodcomprising: a first voltage measuring step of measuring a first voltagethat is a voltage between a terminal of a reference cell belonging tothe plurality of the laminated cell, and the plate; a second voltagemeasuring step of measuring a second voltage that is a voltage between aterminal of the reference cell and, among the pair of laminated cellsfacing the plate, the laminated cell in the reference cell side; and afirst determining step of determining an abnormality based on the firstvoltage and the second voltage.

According to the present disclosure, an abnormality is determined basedon the first voltage and the second voltage, and thus a pore generatedin the outer package film can be detected in an early stage.

The present disclosure also provides a method for determining anabnormality of a battery including a plurality of laminated cellsarranged along a thickness direction and connected in series, and aplate arranged between a pair of the laminated cells, the methodcomprising: a first voltage measuring step of measuring a first voltagethat is a voltage between a terminal of a reference cell belonging tothe plurality of the laminated cell, and the plate; a third voltagemeasuring step of measuring a third voltage that is a voltage between aterminal of the reference cell and, among the pair of laminated cellsfacing the plate, the laminated cell in the opposite side of thereference cell; and a second determining step of determining anabnormality based on the first voltage and the third voltage.

According to the present disclosure, an abnormality is determined basedon the first voltage and the third voltage, and thus a pore generated inthe outer package film can be detected in an early stage.

Effects of Disclosure

A battery system of the present disclosure is capable of detecting apore generated in an outer package film in an early stage.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically exemplifying a whole constitution of avehicle provided with the battery system of the present disclosure.

FIG. 2 is a schematic cross-sectional view exemplifying the all in thepresent disclosure.

FIG. 3 is a schematic cross-sectional view exemplifying the laminatedcell in the present disclosure.

FIG. 4 is a diagram explaining the battery system in the presentdisclosure.

FIG. 5 is a diagram explaining the battery system in the presentdisclosure.

FIG. 6 is a diagram explaining the battery system in the presentdisclosure.

FIG. 7 is a flow chart exemplifying the procedures of the determinationdevice in the present disclosure.

FIG. 8 is a flow chart exemplifying the procedures of the determinationdevice in the present disclosure.

FIG. 9 is a flow chart exemplifying the procedures of the determinationdevice in the present disclosure.

DESCRIPTION OF EMBODIMENTS

The battery system and the method for determining an abnormality of abattery in the present disclosure are hereinafter explained in details.

A. Battery System

FIG. 1 is a diagram schematically exemplifying a whole constitution of avehicle provided with the battery system of the present disclosure.Vehicle 200 comprises battery system 100, Power Control Unit (PCU) 110,Motor Generator (MG) 120, and driving wheel 130. The battery system 100comprises battery 10, monitoring unit 20, and Electronic Control Unit(ECU) 30.

The monitoring unit 20 includes at least a first voltage sensor 20 a, asecond voltage sensor 20 b, and a third voltage sensor 20 c. Inaddition, the ECU 30 conducts various electric control of the vehicle200, and corresponds to a determination device. The ECU 30(determination device) includes at least first obtaining unit, a secondobtaining unit, a third obtaining unit, a first determining unit, asecond determining unit, and a third determining unit as processingblocks to achieve its function, and determines an abnormality based on afirst voltage and, at least one of a second voltage and a third voltage.

According to the present disclosure, the determination device determinesan abnormality based on the first voltage and, at least one of thesecond voltage and the third voltage, so as to allow the battery systemto detect a pore generated in an outer package film in an early stage.Here, as described above, since the outer package film is thin, forexample, a pore may be generated in the outer package film due to aforeign substance mixed during the production of cells.

When a pore is generated, moisture permeates into the cell, and it maycause deterioration of the power generating element. Gas may be alsogenerated from the deteriorated power generating element. Further, whenmoisture permeates into the cell, reactions proceed in the order ofdeterioration of the power generating element due to the permeatedmoisture, and then generation of gas due to the deteriorated powergenerating element; thus, there is a time lag from the generation of apore until the generation of gas. From the above described reasons, whengeneration of gas from the laminated cell is detected with some kind ofmeans from outside (such as with gas sensor), the deterioration of powergenerating element has already proceeded in many cases.

To this, in the present disclosure, the determination device determinesan abnormality based on the first voltage and, at least one of thesecond voltage and the third voltage, and thus the abnormality can bedetected immediately after the pore is generated (before thedeterioration of power generating element proceeds).

In addition, timings when a pore is generated in the outer package filmdue to a foreign substance may be presumably the followings: duringproduction of the cell, during production of the battery, and after theproduction of the battery. On the other hand, after the production ofthe battery, it is presumed that the cell expands and contracts due tocharge and discharge, and over time, the foreign substance go throughthe outer package film to generate a pore.

Further, particularly when the laminated cell is an all solid statebattery, it is required to apply strong restraining pressure to thelaminated cell in order to obtain excellent battery properties. Forexample, necessity of applying strong restraining pressure to thelaminated cell is low in a liquid-based battery using a liquidelectrolyte since the liquid electrolyte has fluidity. In contrast, inan all solid state battery using solid electrolytes such as an inorganicsolid electrolyte, since the solid electrolyte does not have fluidity,it is required to apply strong restraining pressure to the laminatedcell in order to bring the solid electrolytes into contact well witheach other. As a result, for example, even a minute foreign substancethat does not cause problems in the liquid-based battery may be a causeof generating a pore in the outer package film when it comes to the allsolid state battery. For this reason, the problem of generation of apore due to a foreign substance may easily occur when the laminated cellis an all solid state battery.

Also, for example, Japanese Patent Application Laid-Open (JP-A) No.2003-187762 discloses about reducing permeation of moisture into theouter package by doubling a moisture absorbing agent arranged around asealing part. However, for example, a part where the foreign substancemixed during production of the cell generates a pore is not in thesealing part of the outer package film, but is often in a plane part(main surface part). In the present disclosure, the determination devicedetermines an abnormality based on the first voltage and, at least oneof the second voltage and the third voltage, and thus the abnormalitycan be detected quickly.

1. Battery

The battery system in the present disclosure comprises a battery. Thebattery includes a plurality of laminated cells arranged along athickness direction and connected in series, and a plate arrangedbetween a pair of the laminated cells. In addition, the battery 10 ischarged by receiving the power generated by MG 120 via PCU 110 when MG120 generates power.

FIG. 2 is a schematic cross-sectional view exemplifying the battery inthe present disclosure. Battery 10 shown in FIG. 2 includes a pluralityof laminated cells C1 to C5. The plurality of laminated cells C1 to C5are arranged along thickness direction DT so that plane parts (mainsurface parts) face to each other. Further, the plurality of laminatedcells C1 to C5 are connected in series.

Battery 10 shown in FIG. 2 also includes plate 11 arranged between apair of the laminated cells, and end plate 12. The plate is usuallyconductive, and typically a metal plate. Also, the plate may be, forexample, a cool plate to cool the laminated cells.

Battery 10 may include just one of plate 11, but preferably include aplurality thereof. The reason therefor is to improve accuracy ofdetermining an abnormality. For example, in FIG. 2 , plate 11 isarranged respectively between C1 and C2, between C2 and C3, between C3and C4, and between C4 and C5. The number of the plate may be 1, may be2 or more, and may be 5 or more. Incidentally, although not illustratedin particular, the battery in the present disclosure may include a caseconfigured to store the laminated cells and the plate.

FIG. 3 is a schematic cross-sectional view exemplifying one thelaminated cells in the present disclosure. Laminated cell C shown inFIG. 3 includes: power generating element P in which cathode currentcollector 1, cathode layer 2, electrolyte layer 3, anode layer 4, andanode current collector 5 are arranged in a thickness direction in thisorder; outer package film 6 configured to store the power generatingelement P; and insulating part 7 stored in the outer package film 6 andconfigured to prevent short circuit. The cathode current collector 1 isconnected to cathode terminal 1T, and the anode current collector 5 isconnected to anode terminal 5T. The kind of the laminated cell C is notparticularly limited, and may be a lithium ion secondary battery.

The electrolyte layer may contain a solid electrolyte or an electrolytesolution (liquid electrolyte). Incidentally, the all solid state batteryrefers to a battery of which electrolyte layer is a solid electrolytelayer. Examples of the solid electrolyte may include an inorganic solidelectrolyte such as an oxide solid electrolyte and a sulfide solidelectrolyte. In addition, the restraining pressure of the all solidstate battery is, for example, 0.1 MPa or more, and may be 1 MPa ormore.

Further, the outer package film typically includes, from the powergenerating element side, a heat seal layer, a metal layer, and a resinlayer. Examples of the material of the heal seal layer may include anolefin-based resin such as polypropylene (PP) and polyethylene (PE).Examples of the material of the metal layer may include aluminum, analuminum alloy, and stainless steel. Examples of the material of theresin layer may include polyethylene terephthalate (PET) and nylon. Thethickness of the outer package film is, for example, 50 μm or more and200 μm or less.

2. Voltage Sensor

The battery system in the present disclosure comprises the first voltagesensor 20 a and, at least one of the second voltage sensor 20 b and thethird voltage sensor 20 c. For example, in FIG. 1 , monitoring unit 20monitors the condition of battery 10 and outputs a monitoring result toECU 30. The monitoring unit 20 includes at least the first voltagesensor 20 a, the second voltage sensor 20 b, and the third voltagesensor 20 c, and may include current sensor and a temperature sensor asrequired.

The first voltage sensor 20 a measures a first voltage that is a voltagebetween a terminal of a reference cell belonging to the plurality oflaminated cells, and the plate. For example, in FIG. 4 , laminated cellC1 corresponds to the reference cell, and a voltage between terminal Tof C1 and plate 11 corresponds to the first voltage.

As the reference cell, an arbitrary cell belonging to the plurality ofthe laminated cells may be selected. The reference cell may be, forexample, among the plurality of the laminated cells, a cell positionedat the outermost, and may be a cell not positioned at the outermost(positioned at inner side). In addition, the terminal of the referencecell may be a cathode terminal, and may be an anode terminal. Further,the reference cell may be one of the pair of the laminated cells facingthe plate, and may not be the pair of the laminated cells facing theplate.

Also, the first voltage sensor 20 a may select the plate for measuringthe first voltage from the plurality of the plate. For example, in FIG.4 , by controlling ON/OFF of switches SW1 to SW4, the plate formeasuring the first voltage can be selected from the plurality of theplate. In this manner, the battery system in the present disclosure maycomprise a switching device configured to select the plate.

The battery system in the present disclosure may comprise the secondvoltage sensor 20 b configured to measure a second voltage that is avoltage between a terminal of the reference cell and, among the pair oflaminated cells facing the plate (plate for measuring the firstvoltage), the laminated cell in the reference cell side. Incidentally,“among the pair of laminated cells facing the plate, the laminated cellin the reference cell side” refers to, among the pair of the laminatedcells facing the plate, the laminated cell having a small voltage withrespect to the reference cell.

The battery system of the present disclosure may further comprise thethird voltage sensor 20 c configured to measure a third voltage that isa voltage between a terminal of the reference cell and, among the pairof laminated cells facing the plate (plate for measuring the firstvoltage), the laminated cell in the opposite side of the reference cell.Incidentally, “among the pair of laminated cells facing the plate, thelaminated cell in the opposite side of the reference cell” refers to,among the pair of the laminated cells facing the plate, the laminatedcell having a large voltage with respect to the reference cell. In someembodiments, the second voltage sensor 20 b and the third voltage sensor20 c may be a common voltage sensor such that the second voltage sensor20 b is, for example, configured to measure the voltage of eachlaminated cell, and the determination device may include a calculationunit configured to calculate at least one of the second voltage and thethird voltage based on the measurement path of the first voltage.

3. Determination Device

(1) Constitution of Determination Device

The battery system in the present disclosure comprises a determinationdevice. The determination device is configured to detect a pore in theouter package film due to a foreign substance. For example, in FIG. 1 ,ECU 30 includes a CPU (Central Processing Unit), a memory, and an inputand output port configured to input and output various signals. Examplesof the memory includes a ROM (Read Only Memory), a RAM (Random AccessMemory), and a rewritable nonvolatile memory. The CPU processes programsrecorded in the memory to conduct various controls. Various controlsconducted by ECU can also be processed by a dedicated hardware(electronic circuit), but not limited to software.

The determination device includes at least an obtaining unit and adetermining unit as processing blocks to achieve its function.

The first obtaining unit is configured to obtain a first voltage fromthe first voltage sensor 20 a. For example, as shown in FIG. 4 , whenforeign substance X is present in the right side of laminated cell C3,the voltage 1 is generated by turning on the switch SW3 connected toplate 11 arranged between the laminated cell C3 and laminated cell C4.The first voltage (V₁) is usually equal to the total of the voltages(V_(C1)+V_(C2)+V_(C3)) of the laminated cells C1 to C3. In other words,the voltage (V_(C1)+V_(C2)+V_(C3)) is generated as a voltage between theterminal T of the laminated cell C1 that is a reference cell and, theplate 11. Incidentally, the foreign substance X is typically aconductive foreign substance.

In addition, as shown in FIG. 5 , when foreign substance X is present inthe left side of the laminated cell C4, the first voltage is generatedby turning on the switch SW3 connected to the plate 11 arranged betweenthe laminated cell C3 and the laminated cell C4. The first voltage (V₁)is usually equal to the total of the voltages(V_(C1)+V_(C2)+V_(C3)+V_(C4)) of the laminated cells C1 to C4.

Further, as shown in FIG. 6 , when foreign substance X is present in theright side of laminated cell C5, the first voltage is generated byturning on the switch SW5 connected to end plate 12 arranged on onesurface side of the laminated cell C5. The first voltage (V₁) is usuallyequal to the total of the voltages (V_(C1)+V_(C2)+V_(C3)+V_(C4)+V_(C5))of the laminated cells C1 to C5. In this manner, in the presentdisclosure, the first voltage may be calculated from the voltage betweenthe terminal of the reference cell and the end plate.

The determination device in the present disclosure may include a secondobtaining unit configured to obtain a second voltage from the secondvoltage sensor 20 b, and first determination unit configured todetermine an abnormality based on the first voltage and the secondvoltage. For example, as shown in FIG. 4 , when foreign substance X ispresent in the right side of the laminated cell C3, obtained is secondvoltage (V₂) that is a voltage between terminal T of the laminated cellC1 which is a reference cell and, the laminated cell C3 in the referencecell (laminated cell C1) side, among a pair of laminated cells C3 and C4facing corresponding plate 11. In this case, the second voltage (V₂) isequal to the total of the voltages (V_(C1)+V_(C2)+V_(C3)) of laminatedcells C1 to C3. The first determining unit determines an abnormalitywhen V₁ is equal to V₂.

In addition, as shown in FIG. 5 , when foreign substance X is present inthe left side of the laminated cell C4, obtained is second voltage (V₂)that is a voltage between terminal T of the laminated cell C1 which is areference cell and, the laminated cell C3 in the reference cell(laminated cell C1) side, among a pair of laminated cells C3 and C4facing corresponding plate 11. In this case, the second voltage (V₂) isequal to the total of the voltages (V_(C1)+V_(C2)+V_(C3)) of laminatedcells C1 to C3. As described above, the first voltage (V₁) in FIG. 5 isusually equal to the total of the voltages (V_(C1)+V_(C2)+V_(C3)+V_(C4))of the laminated cells C1 to C4; thus, V₁ is larger than V₂. The firstdetermining unit determines an abnormality when V₁ is larger than V₂.

The first determining unit is configured to determine an abnormalitybased on the first voltage and the second voltage. As described above,the first determining unit determines an abnormality when V₁ is equal toV₂, or when V₁ is larger than V₂. The case “V₁ is equal to V₂” includeswhen, for example, 0.9≤V₁/V₂≤1.05 is satisfied, in consideration of theresistance of the plate and an error of the voltage sensor. Inparticular, when V₁ is in a range of V₂±2.5%, it can be said that thepossibility a pore has been generated in the outer package film isextremely high. Meanwhile, the case “V₁ is larger than V₂” is usually1<V₁/V₂, and it may be 1.5≤V₁/V₂.

The determination device in the present disclosure may include a thirdobtaining unit configured to obtain a third voltage from the thirdvoltage sensor 20 c, and a second determining unit configured todetermine an abnormality based on the first voltage and the thirdvoltage when the first determining unit determines an abnormality. Asshown in FIG. 5 , when foreign substance X is present in the left sideof the laminated cell C4, obtained is a third voltage (V₃) that is avoltage between terminal T of the laminated cell C1 which is a referencecell and, laminated cell C4 in the opposite side of the reference cell(laminated cell C1), among a pair of the laminated cells C3 and C4facing corresponding plate 11. In this case, the voltage (V₃) is equalto the total of the voltages (V_(C1)+V_(C2)+V_(C3)+V_(C4)) of thelaminated cells C1 to C4.

As described above, the first voltage (V₁) in FIG. 5 is usually equal tothe total of the voltages (V_(C1)+V_(C2)+V_(C3)+V_(C4)) of the laminatedcells C1 to C4; thus, V₁ is equal to V₃. The second determining unitdetermines an abnormality when V₁ is equal to V₃. The case “V₁ is equalto V₃” includes when, for example, 0.9≤V₁/V₃≤1.05 is satisfied, inconsideration of the resistance of the plate and an error of the voltagesensor. In particular, when V₁ is in a range of V₃±2.5%, it can be saidthat the possibility a pore has been generated in the outer package filmis extremely high. In the present disclosure, the second determiningunit may determine an abnormality based on the first voltage and thethird voltage when the first determining unit determines an abnormality.

Further, the determination device may include a specifying unitconfigured to specify an abnormal laminated cell based on the firstvoltage, when the first determining unit or the second determining unitdetermines an abnormality. In that case, the battery system may comprisea display unit configured to notify to change the abnormal laminatedcell specified by the specifying unit or to change the battery includingthe abnormal laminated cell. The display unit is, for example, a liquidcrystal display.

(2) Procedures of Determination Device

FIG. 7 is a flow chart exemplifying the procedures of the determinationdevice in the present disclosure. As shown in FIG. 7 , in step S1,obtained from the first voltage sensor 20 a is first voltage (V₁) thatis a voltage between a terminal of the reference cell belonging to theplurality of the laminated cells and, the plate. In step S2, whether thefirst voltage (V₁) is generated or not is determined. For example, asshown in FIG. 4 , when foreign substance X is present in the right sideof the laminated cell C3, the first voltage (V₁) would not be generatedby turning on the switch SW2. In that case, the procedure goes to stepS3: determine no abnormality, and it is the end of the process.

On the other hand, for example, as shown in FIG. 4 , when foreignsubstance X is present in the right side of the laminated cell C3, thefirst voltage (V₁) is generated by turning on the switch SW3. In thatcase, the procedure goes to step S4. In the step S4, obtained from thesecond voltage sensor 20 b is a second voltage (V₂) that is a voltagebetween the terminal of the reference cell and, among the pair of thelaminated cells facing the plate, the laminated cell in the referenceside cell.

In step S5, whether the first voltage (V₁) and the second voltage (V₂)satisfy V₁≥V₂ or not is determined. When V₁≥V₂ is not satisfied, theprocedure goes back to the step S1. After that, the steps S1 to S5 maybe repeated until V₁≥V₂ is satisfied, and the procedure may go to stepS6 when the specified repeating number exceeds. On the other hand, whenV₁≥V₂ is satisfied, the procedure goes to the step S6: determineabnormality. In step S7, an abnormal laminated cell is specified basedon the first voltage (V₁), and in step S8, notification to change thespecified abnormal laminated cell or to change the battery including theabnormal laminated cell is prompted, and it is the end of the process.

FIG. 8 is a flow chart exemplifying the procedures of the determinationdevice in the present disclosure. Steps S1 to S5 in FIG. 8 are the sameas the steps S1 to S5 in FIG. 7 . In step S6, obtained from the thirdvoltage sensor 20 c is a third voltage (V₃) that is a voltage betweenthe terminal of the reference cell and, among the pair of the laminatedcells facing the plate, the laminated cell in the opposite side of thereference cell.

In step S7, whether the first voltage (V₁) and the third voltage (V₃)satisfy V₁=V₃ or not is determined. When V₁=V₃ is not satisfied, theprocedure goes back to the step S1. After that, the steps S1 to S7 maybe repeated until V₁=V₃ is satisfied, and the procedure may go to stepS8 when the specified repeating number exceeds. On the other hand, whenV₁=V₃ is satisfied, the procedure goes to step S8: determineabnormality. In step S9, an abnormal laminated cell is specified basedon the first voltage (V₁), and in step S10, notification to change thespecified abnormal laminated cell or to change the battery including theabnormal laminated cell is prompted, and it is the end of the process.

FIG. 9 is a flow chart exemplifying the procedures of the determinationdevice in the present disclosure. Steps S1 to S3 in FIG. 9 are the sameas the steps S1 to S3 in FIG. 7 . In step S4, obtained from the thirdvoltage sensor 20 c is a third voltage (V₃) that is a voltage betweenthe terminal of the reference cell and, among the pair of the laminatedcells facing the plate, the laminated cell in the opposite side of thereference cell.

In step S5, whether the first voltage (V₁) and the third voltage (V₃)satisfy V₁=V₃ or not is determined. When V₁=V₃ is not satisfied, theprocedure goes back to the step S1. After that, the steps S1 to S5 maybe repeated until V₁=V₃ is satisfied, and the procedure may go to stepS6 when the specified repeating number exceeds. On the other hand, whenV₁=V₃ is satisfied, the procedure goes to step S6: determineabnormality. In step S7, an abnormal laminated cell is specified basedon the first voltage (V₁), and in step S8, notification to change thespecified abnormal laminated cell or to change the battery including theabnormal laminated cell is prompted, and it is the end of the process.

In some embodiments, the determination device repeats the procedures ata specified interval. Further, the determination device may repeat theprocedures with a fixed reference cell, or with a different referencecell in each time. Similarly, the determination device may repeat theprocedures with a fixed plate for measuring the second voltage, or adifferent plate for measuring the second voltage in each time.

B. Method for Determining Abnormality of Battery

A first embodiment of the method for determining an abnormality of abattery is a method for determining an abnormality of a batteryincluding a plurality of laminated cells arranged along a thicknessdirection and connected in series, and a plate arranged between a pairof the laminated cells, the method comprising: a first voltage measuringstep of measuring a first voltage that is a voltage between a terminalof a reference cell belonging to the plurality of the laminated cell,and the plate, a second voltage measuring step of measuring a secondvoltage that is a voltage between a terminal of the reference cell and,among the pair of laminated cells facing the plate, the laminated cellin the reference cell side, and a first determining step of determiningan abnormality based on the first voltage and the second voltage.

According to the first embodiment, an abnormality is determined based onthe first voltage and the second voltage, and thus a pore generated inthe outer package film can be detected in an early stage.

The method for determining an abnormality of the battery may include athird voltage measuring step of measuring a third voltage that is avoltage between a terminal of the reference cell and, among the pair oflaminated cells facing the plate, the laminated cell in the oppositeside of the reference cell. Further, the method for determining anabnormality of the battery may include a second determining step ofdetermining an abnormality based on the first voltage and the thirdvoltage when an abnormality is determined in the first determining step.

The method for determining an abnormality of a battery in the secondembodiment is a method for determining an abnormality of a batteryincluding a plurality of laminated cells arranged along a thicknessdirection and connected in series, and a plate arranged between a pairof the laminated cells, the method comprising: a first voltage measuringstep of measuring a first voltage that is a voltage between a terminalof a reference cell belonging to the plurality of the laminated cell,and the plate, a third voltage measuring step of measuring a thirdvoltage that is a voltage between a terminal of the reference cell and,among the pair of laminated cells facing the plate, the laminated cellin the opposite side of the reference cell, and a second determiningstep of determining an abnormality based on the first voltage and thethird voltage.

According to the second embodiment, an abnormality is determined basedon the first voltage and the third voltage, and thus a pore generated inthe outer package film can be detected in an early stage.

Incidentally, each step in the method for determining an abnormality ofthe battery are in the same contents as those described in “A. Batterysystem” above; thus, the descriptions herein are omitted.

The present disclosure is not limited to the embodiments. Theembodiments are exemplification, and any other variations are intendedto be included in the technical scope of the present disclosure if theyhave substantially the same constitution as the technical idea describedin the claim of the present disclosure and offer similar operation andeffect thereto.

REFERENCE SIGNS LIST

-   -   1 cathode current collector    -   2 cathode layer    -   3 electrolyte layer    -   4 anode layer    -   5 anode current collector    -   6 outer package film    -   10 battery    -   11 plate    -   20 monitoring unit    -   20 a first voltage sensor    -   20 b second voltage sensor    -   20 c third voltage sensor    -   30 ECU    -   100 battery system

What is claimed is:
 1. A battery system comprising: a battery includinga plurality of laminated cells arranged along a thickness direction andconnected in series, and a plate arranged between a pair of thelaminated cells, a first voltage sensor configured to measure a firstvoltage that is a voltage between a terminal of a reference cellbelonging to the plurality of laminated cells, and the plate, a secondvoltage sensor configured to measure a second voltage that is a voltagebetween the terminal of the reference cell and, among the pair oflaminated cells that the plate is between, a laminated cell on areference cell side of the plate, and an electronic control unit; andthe electronic control unit includes: a first obtaining unit configuredto obtain the first voltage from the first voltage sensor, a secondobtaining unit configured to obtain the second voltage from the secondvoltage sensor, and a first determining unit configured to determine anabnormality based on the first voltage and the second voltage.
 2. Thebattery system according to claim 1, wherein the battery system furthercomprises a third voltage sensor configured to measure a third voltagethat is a voltage between the terminal of the reference cell and, amongthe pair of laminated cells that the plate is between, a laminated cellon an opposite side of the plate from the reference cell side of theplate, and the electronic control unit further includes: a thirdobtaining unit configured to obtain the third voltage from the thirdvoltage sensor, and a second determining unit configured to determine anabnormality based on the first voltage and the third voltage when thefirst determining unit determines an abnormality.
 3. A battery systemaccording to claim 1, wherein the battery includes a plurality ofplates, and the electronic control unit is configured to select theplate for measuring the first voltage from the plurality of plates.
 4. Abattery system comprising: a battery including a plurality of laminatedcells arranged along a thickness direction and connected in series, anda plate arranged between a pair of the laminated cells, a first voltagesensor configured to measure a first voltage that is a voltage between aterminal of a reference cell belonging to the plurality of laminatedcells, and the plate, a supplemental voltage sensor configured tomeasure a supplemental voltage that is a voltage between the terminal ofthe reference cell and, among the pair of laminated cells that the plateis between, a laminated cell on an opposite side from a reference cellside of the plate, and an electronic control unit; and the electroniccontrol unit includes: a first obtaining unit configured to obtain thefirst voltage from the first voltage sensor, a supplemental obtainingunit configured to obtain the supplemental voltage from the supplementalvoltage sensor, and a second determining unit configured to determine anabnormality based on the first voltage and the supplemental voltage. 5.A method for determining an abnormality of a battery including aplurality of laminated cells arranged along a thickness direction andconnected in series, and a plate arranged between a pair of thelaminated cells, the method comprising: a first voltage measuring stepof measuring, by a first voltage sensor, a first voltage that is avoltage between a terminal of a reference cell belonging to theplurality of the laminated cell, and the plate, a second voltagemeasuring step of measuring, by a second voltage sensor, a secondvoltage that is a voltage between the terminal of the reference celland, among the pair of laminated cells that the plate is between, alaminated cell on a reference cell side of the plate, and a firstdetermining step of determining, by an electronic control unit, anabnormality based on the first voltage and the second voltage.
 6. Amethod for determining an abnormality of a battery including a pluralityof laminated cells arranged along a thickness direction and connected inseries, and a plate arranged between a pair of the laminated cells, themethod comprising: a first voltage measuring step of measuring, by afirst voltage sensor, a first voltage that is a voltage between aterminal of a reference cell belonging to the plurality of the laminatedcell, and the plate, a supplemental voltage measuring step of measuring,by a supplemental voltage sensor, a supplemental voltage that is avoltage between the terminal of the reference cell and, among the pairof laminated cells that the plate is between, a laminated cell on anopposite side from a reference cell side from the plate, and a seconddetermining step of determining, by an electronic control unit, anabnormality based on the first voltage and the supplemental voltage.